1. Field of the Invention
The present invention relates to an electrostatic latent image-developing toner (referred to below simply as a “toner”) for use in developing electrostatic latent images (electrostatic images) in, for example, electrophotographic, electrostatic recording and electrostatic printing processes. The invention also relates to a method of producing such a toner. More specifically, the invention relates to a toner which achieves a good balance of low-temperature fixability and heat-resistant storability and also provides an excellent fixed image reliability, and to a method of producing such a toner.
2. Description of the Related Art
Methods of visualizing image information via an electrostatic latent image, such as electrophotography, are currently employed in various fields, and there exists a desire for improvements in performance, including higher image quality and lower energy consumption. In electrophotography, first an electrostatic latent image is formed on an electrophotographic photoreceptor (image-bearing member) by way of charging and light exposure steps. The electrostatic latent image is then developed with a toner-containing developer, thereby giving a visualized image (fixed image) via a transfer step and a fixing step.
In this process, the fixing step is a step that requires a relatively large amount of energy, and so developing a system and materials which achieve both lower energy consumption and higher image quality has been an important technical challenge. One approach that can be taken from the materials aspect is to both enhance the releasability of the toner from the fixing member by including wax in the toner, and also increase the low-temperature fixability by plasticizing the binder resin with wax that has melted during fixing.
From the standpoint of enhancing the low-temperature fixability with wax, it is preferable to use a low-melting wax. On the other hand, because low-melting waxes melt at low temperatures, the heat-resistant storability of the toner is lost, making it difficult to achieve both low-temperature fixability and heat-resistant storability.
Art is known which, by using wax having a narrow melting temperature range, allows the wax to rapidly melt at the temperature at which fixing is carried out without melting when the toner is stored. Japanese Patent Application Laid-open No. 2012-13859 discloses art which uses a wax having, as measured with a differential scanning calorimeter in a toner, half width of an endothermic peak of 8° C. or less.
However, from the standpoint of the rubbing resistance of the fixed image and image non-uniformity, using a wax having a narrow melting temperature width is disadvantageous. Japanese Patent Application Laid-open No. 2011-70001 discloses art which uses a wax having a somewhat broad half width; specifically, the half width of the endothermic peak for a release agent, as determined with a differential scanning calorimeter, is not less than 10° C. and not more than 18° C.